Stackman Robert W, Golob Edward J, Bassett Joshua P, Taube Jeffrey S
Department of Psychological and Brain Sciences, Center for Cognitive Neuroscience, Dartmouth College, Hanover, New Hampshire 03755, USA.
J Neurophysiol. 2003 Nov;90(5):2862-74. doi: 10.1152/jn.00346.2003. Epub 2003 Jul 30.
A subset of neurons in the rat limbic system encodes head direction (HD) by selectively discharging when the rat points its head in a preferred direction in the horizontal plane. The preferred firing direction is sensitive to the location of landmark cues, as well as idiothetic or self-motion cues (i.e., vestibular, motor efference copy, proprioception, and optic flow). Previous studies have shown that the preferred firing direction remains relatively stable (average shift +/- 18 degrees ) after the rat walks from a familiar environment into a novel one, suggesting that without familiar landmarks, the preferred firing direction can be maintained using idiothetic cues, a process called directional path integration. This study repeated this experiment and manipulated the idiothetic cues available to the rat as it moved between the familiar and novel environment. Motor efference copy/proprioceptive cues were disrupted by passively transporting the animal between the familiar and novel environment. Darkening the room as the animal moved to the novel environment eliminated optic flow cues. HD cell preferred firing directions shifted in the novel environment by an average of 30 degrees after locomotion from the familiar environment with the room lights off; by an average of 70 degrees after passive transport from the familiar environment with the room lights on; and by an average of 67 degrees after passive transport with the room lights off. These findings are consistent with the view that motor efference copy/proprioception cues are important for maintaining the preferred firing direction of HD cells under conditions requiring path integration.
大鼠边缘系统中的一部分神经元通过在大鼠将头部指向水平面中的偏好方向时选择性放电来编码头部方向（HD）。偏好的放电方向对地标线索的位置以及自身运动线索（即前庭、运动传出副本、本体感觉和视觉流）敏感。先前的研究表明，在大鼠从熟悉的环境进入新环境后，偏好的放电方向保持相对稳定（平均偏移±18度），这表明在没有熟悉地标的情况下，可以使用自身运动线索来维持偏好的放电方向，这一过程称为定向路径整合。本研究重复了该实验，并在大鼠在熟悉和新环境之间移动时操纵其可用的自身运动线索。通过在熟悉和新环境之间被动运输动物来破坏运动传出副本/本体感觉线索。当动物移动到新环境时使房间变暗消除了视觉流线索。在大鼠从熟悉环境在关灯情况下移动到新环境后，HD细胞偏好的放电方向在新环境中平均偏移30度；在开灯情况下从熟悉环境进行被动运输后平均偏移70度；在关灯情况下进行被动运输后平均偏移67度。这些发现与以下观点一致，即在需要路径整合的条件下，运动传出副本/本体感觉线索对于维持HD细胞偏好的放电方向很重要。
